Flexible scan field

ABSTRACT

An energy beam machining system includes an emitter for emitting an energy beam and beam adjusting optics, such as a zoom telescope, for adjusting the pupil size of the system to multiple values. The adjusting of the pupil size can be carried out automatically, semi-automatically, or manually. In manual modes, instructions can be presented to the operator (e.g., via a monitor or pre-programmed audio instruction) indicating how to adjust pupil size. A focus lens focuses the adjusted beam directed along each path at a different focal point within a scan field encompassed in the field of view of the focus lens. Beam directing optics are configured to enable multiple scan fields within the field of view of the focus lens.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/512,043, filed Oct. 17, 2003, which is herein incorporated in itsentirety by reference.

FIELD OF THE INVENTION

The invention relates to energy beam scanning, and more particularly, tooptimizing characteristics of a laser beam to the applicable machiningoperations.

BACKGROUND OF THE INVENTION

Energy beams, such as laser beams, are commonly used in numerousdifferent types of machining operations, including what are oftenreferred to as micro-machining operations. In conventionalmicro-machining operations, laser beams are used to machine features onsubstrates, such as printed circuit boards and panels. One typicalmicro-machining operation involves the laser trimming of resistors andcapacitors printed on a substrate.

FIG. 1 depicts a conventional laser beam micro-machining system 10 ofthe type used for resistor trimming. The system 10 includes a laser beamemitter 15 operating under the control of the system controller 55. Theemitted laser beam 20 passes through a fixed beam expander 25 to thescan subsystem 30.

As shown, the scan subsystem 30 includes beam directing optics 35 and afocus lens 40. The scan system 30 also operates under the control of thesystem controller 55. The beam 20 is directed by the beam directingoptics 35 through the focus lens 40. The beam directing optics 35includes a pair of galvo driven mirrors. The focus lens 40 has a fieldof view and focuses the beam 20 so that the beam 20 impinges point 22 ona resistor 45 on the substrate 50 to perform the trimming operation. AnX-Y stage 52 is provided to move the substrate 50 in two axes toposition the resistor under the field of view of the lens 40. The focalpoint 22 of the directed beam impinges on the substrate 50, so as toperform the trimming operation.

The fixed beam expander 25 establishes the size (effective entrancepupil) of the beam entering the scan system 30. As shown in FIG. 1,using the fixed beam expander 25 results in the collimated beam enteringthe scan subsystem having a pupil size B which corresponds to a spotsize B′ of the beam at the focal point 22 on the focal surface. Thus,should a larger or smaller spot size be desired, the fixed beam expander25 must be replaced with another beam expander having the appropriatebeam expansion ratio to achieve the desired spot size.

Generally, if a larger spot size is desired at focal point 22, a fixedbeam expander that will cause the effective entrance pupil size of thebeam entering the scan subsystem to be less than B must be substitutedfor the fixed beam expander 25. On the other hand, if a smaller spotsize is desired at the focal point 22, a fixed beam expander that willcause the effective entrance pupil size of the beam entering the scansubsystem to be greater than B must be substituted for the fixed beamexpander 25. In any such cases, the beam expander must be changed.

In addition, it has recently become necessary for such machines as shownin FIG. 1 to be used in machining features on substrates having varioussizes and/or various shapes. Varying the size and/or shape of thesubstrate will result in a need to vary the size of the scan field thatmust be covered by a focused beam having the desired spot size. The stepsize of the X-Y stage movement may also have to correspondingly change.Accuracy of beam placement and the degree of telecentricity may alsovary with the changes in the field size.

The achievable spot size within the scan field in a conventional lasermachining system is governed by a number of factors, including the pupilsize and the focus lens characteristics. Relevant focus lenscharacteristics include the lens focal length, the lens performancedegradation at large angles, the telecentricity of the focus lens, andthe complexity and cost of the focus lens.

With regard to degradation, it will be understood that focusing a beamthrough the outside area of the focus lens will often result in degradedperformance when smaller spots are desired. In addition, beam positionalaccuracy may be degraded near the perimeter of the focal surface whenthe field size is increased. Moreover, in a non-telecentric system,telecentricity may also be degraded near the perimeter of the focalsurface at increased field sizes.

To address a large scan field, a focus lens having a large field of viewand a long focal length must be used. Without increasing the beam pupilsize, this will result in the beam having a large spot size at the focalsurface. However, if the pupil size is increased, the size of themirrors or other beam directing components must also be increased,thereby degrading dynamic performance. To achieve a smaller beam spotsize at the focal surface, without increasing the focal length, the beampupil size at the beam directing optics must be increased.

For some scan field applications, a focus lens having a high degree oftelecentricity may be required. However, if the packing density of thefeatures to be machined is high, resulting in the need for a small beamspot size at the focal surface, then the complexity and cost ofdesigning and manufacturing such a focus lens can be quite high.

Accordingly, conventional approaches to machining features at varyingpacking densities on substrates having different sizes and/or shapes isto utilize separate systems, with a fixed field size and X-Y stage stepsize, optimized for each particular machining application, as required.A separate focus lens for different fields is required. The differentfocus lenses are manually installed and de-installed in the scansubassembly prior to initiating of the machining of features for aparticular job. This results in increased manufacturing costs.

Hence, the need exists for a machining system capable of machiningfeatures at various packing densities on substrates having differentsizes and/or shapes without resorting to a different system or manuallychanging the focus lens in the scanning subassembly.

SUMMARY OF THE INVENTION

One embodiment of the present invention provides a flexibly optimizedmaterial processing system. The system includes a laser emitterconfigured to emit a laser beam. Beam adjusting optics having a beamexpansion ratio are configured to adjust the emitted laser beam byadjusting the beam expansion ratio. Beam directing optics are configuredto provide a variable effective pupil corresponding to the adjustedlaser beam. The beam directing optics are further configured to directthe adjusted beam to one or more targets within a scan field. A lens,having a field of view encompassing at least the scan field, isconfigured to focus the directed laser beam onto the one or more targetswithin the scan field. A control processor is configured to receiveinput corresponding to a material processing parameter, and to issue atleast one optimized control signal based on the at least one materialprocessing parameter. The beam adjusting optics can be, for example, azoom telescope. The beam directing optics can be, for example, one ormore galvanometer mirror scanners. The system may further include amotion system that is configured to move a work piece containing atleast one target relative to the scan field, and to position the atleast one target within the scan field for processing (e.g., lasertrimming of a circuit component or link blasting in a memory array).

In one such embodiment, the optimized control signal is an optimumeffective pupil of the beam directing optics corresponding to a scanfield dimension. In another such embodiment, the optimized controlsignal is an optimum scan field dimension corresponding to one of theeffective pupil of the beam directing optics, a focused laser beam spotsize, a positional accuracy, a scanning speed, a material handling stepsize of a motion system, and a telecentricity value. In another suchembodiment, the optimized control signal is an optimum material handlingstep size corresponding to one of a scan field dimension, a step periodof a motion system, a substrate dimension, and a dimension of a selectedarea of a substrate. Note that the beam adjusting optics can, forinstance, be automatically or manually operated to adjust the beamexpansion ratio according to an optimum beam expansion ratio valuedetermined by the controller.

The material processing parameter can be, for example, any one of a spotsize, a substrate dimension, a dimension of a selected area of asubstrate, an orientation of a selected area of a substrate, a packingdensity, a step time of a motion system, a step size of a motion system,a number of steps of a motion system, a scan speed, a positionalaccuracy, a telecentricity value, and a desired spot quality. Thecontroller can be configured to determine at least one optimized valueof the beam expansion ratio, a scan field dimension, and a materialhandling step size of a motion system, based on the material processingparameter.

In one particular case, the beam expansion ratio is a first value, andthe scan field is a first scan field. Here, the beam adjusting opticsare further configured to again adjust the beam expansion ratio from thefirst value to a second value, and the beam directing optics are furtherconfigured to direct the again adjusted beam to a target within thesecond scan field. In one such embodiment, the first scan field has afirst size and the second scan field has a second size. In another suchembodiment, the first scan field has a first shape and the second scanfield has a second shape. In another particular case, the field of viewof the lens encompasses at least a first scan field and a second scanfield, and is further configured to focus a first directed laser beamwith a first effective pupil size onto one or more targets within thefirst scan field, and to focus a second directed laser beam with asecond effective pupil size onto one or more targets within the secondscan field, wherein at least one scan field size is limited by spot sizedegradation over the field of view.

The system may include a control processor that is configured to receivean input identifying the scan field, and to issue scan control signalsbased on the received input. Here, the beam directing optics are furtherconfigured to direct the adjusted beam in accordance with the issuedscan control signals. The system may include a control processor that isconfigured to receive an input corresponding to a focused beam spotsize, and to issue spot size control signals based on the receivedinput. Here, the beam adjusting optics are further configured to adjustthe beam expansion ratio in accordance with the issued spot size controlsignals. The system may include a control processor that is configuredto receive an input corresponding to a beam spot size, and to issue spotsize control signals based on the received input. Here, a displaymonitor can be configured to display parameters for manually operatingthe beam adjusting optics to adjust the beam expansion ratio inaccordance with the issued spot size control signals. The system mayinclude a control processor that is configured to receive an inputidentifying the scan field, and to issue motion control signals based onthe received input. Here, a motion system is configured to move a workpiece relative to the scan field in accordance with the issued motioncontrol signals.

Another embodiment of the present invention provides a method offlexibly optimized material processing. The method includes receiving atleast one material processing parameter relevant to impinging a workpiece with a laser beam. The method continues with issuing at least oneoptimized control signal based on the at least one material processingparameter. The method further includes adjusting the laser beam to afirst adjusted beam in accordance with the at least one optimizedcontrol signal, and directing the adjusted laser beam to one or moretargets within a first scan field. The method proceeds with focusing thedirected beam onto the one or more targets within the first scan field.Note that adjusting the laser beam to a first adjusted beam may includeautomatically or manually adjusting a beam expansion ratio to a firstoptimized value.

In one such embodiment, issuing at least one optimized control signalincludes issuing an optimum effective pupil corresponding to a scanfield dimension. In another such embodiment, issuing at least oneoptimized control signal includes issuing an optimum scan fielddimension corresponding to one of an effective pupil, a process beamspot size, a positional accuracy, a scanning speed, a material handlingstep size, and a telecentricity value. In another such embodiment,issuing at least one optimized control signal includes issuing anoptimum material handling step size corresponding to one of a scan fielddimension, a step period of a motion system, a substrate dimension, anda dimension of a selected area of a substrate. In another suchembodiment, issuing at least one optimized control signal includesissuing an optimum value of at least one of a beam expansion ratio, ascan field dimension, and a material handling step size based on theprocess parameter. The at least one material processing parameterreceived can be, for example, any one of a spot size, a substratedimension, a dimension of a selected area of a substrate, orientation ofa selected area of a substrate, packing density, a step time of a motionsystem, step size of a motion system, a number of steps of a motionsystem, a scan speed, a positional accuracy, a telecentricity, and aspot quality.

In one particular case, adjusting the laser beam to a first adjustedbeam includes adjusting a beam expansion ratio to a first value. Here,the method includes further adjusting the beam expansion ratio to asecond value, and directing the further adjusted beam to one or moretargets within a second scan field. In one such case, the first scanfield has a first size and the second scan field has a second size. Inanother such case, the first scan field has a first shape and the secondscan field has a second shape. Adjusting the laser beam can be carriedout, for example, using a zoom telescope. Directing the adjusted laserbeam can be carried out, for example, using one or more galvanometermirror scanners. In another particular case, adjusting the laser beam toa first adjusted beam includes adjusting a beam expansion ratio to afirst value, where the method further includes adjusting the beamexpansion ratio to a second value to provide a second adjusted beam,directing the second adjusted beam to one or more targets within asecond scan field, and focusing the second adjusted beam onto one ormore targets within the second scan field. Here, at least one scan fieldsize is limited by spot size degradation over a field of view. Inanother particular case, the first scan field size is limited by spotsize degradation at a first effective pupil size over the field of view,and the second scan field size is limited by spot size degradation at asecond effective pupil size over the field of view.

The method may include receiving an input identifying a scan fielddimension, issuing scan control signals based on the received input, anddirecting the adjusted beam in accordance with the issued scan controlsignals. The method may include receiving an input identifying a focusedbeam spot size, issuing spot size control signals based on the receivedinput, and adjusting a beam expansion ratio in accordance with theissued spot size control signals. The method may include receiving aninput identifying a focused beam spot size, issuing spot size controlsignals based on the received input, and displaying parameters formanually adjusting a beam expansion ratio in accordance with the issuedspot size control signals. The method may include receiving an inputidentifying a scan field dimension, and issuing motion control signalsbased on the received input, to move the work piece relative to the scanfield in accordance with the issued scan control signals.

Another embodiment of the present invention provides a materialprocessing system. The system includes an emitter configured to emit alaser beam, a control processor configured to issue optimized controlsignals, and beam adjusting optics configured to adjust the emittedlaser beam in accordance with at least one of the optimized controlsignals. A lens, having a field of view, is configured to focus theadjusted beam onto one or more targets within a scan field encompassedby the field of view. Beam directing optics are configured to direct theadjusted beam to at least one of the one or more targets within the scanfield. In one such case, the scan field is a first scan field. Here, thebeam adjusting optics are further configured to again adjust the emittedlaser beam, and the lens is further configured to focus the againadjusted beam onto one or more targets within a second scan fieldencompassed by the field of view. In addition, the beam directing opticsare further configured to direct the again adjusted beam within thesecond scan field. The beam directing optics can be further configuredto direct the adjusted beam in accordance with at least one of theoptimized control signals. The system may further include a motionsystem configured to move a work piece relative to the scan field inaccordance with at least one of the control signals.

The features and advantages described herein are not all-inclusive and,in particular, many additional features and advantages will be apparentto one of ordinary skill in the art in view of the drawings,specification, and claims. Moreover, it should be noted that thelanguage used in the specification has been principally selected forreadability and instructional purposes, and not to limit the scope ofthe inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a conventional micro-machining system.

FIG. 2 depicts a micro-machining system configured in accordance withone embodiment of the present invention.

FIG. 3A depicts exemplary laser beam spots at the focal point achievableusing the micro-machining system of FIG. 2.

FIG. 3B depicts the exemplary laser beam spots of FIG. 3A in relation tothe scan field.

FIG. 4 depicts example variations in the scan field that can beaccommodated by the micro-machining system of FIG. 2.

FIG. 5 is a detailed depiction of a micro-machining system controllerconfigured in accordance with one embodiment of the present invention.

FIG. 6 depicts a look-up table usable to control the micro-machiningsystem shown in FIG. 2, in accordance with one embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention can be employed to machine featuresat various sizes and/or packing densities on work pieces havingdifferent sizes and/or shapes. This machining can be accomplishedwithout using different systems and without manually installing andde-installing different focus lenses in the scan subassembly. Variousmaterial processing parameters including, for example, field size,accuracy, telecentricity, step size and/or spot size can be flexiblyoptimized for a particular application.

Overview

FIG. 2 depicts a micro-machining system 110 configured in accordancewith one embodiment of the present invention. The system could be usedfor various types of machining operations, such as a trimming operationfor untrimmed circuit elements (e.g., film resistors, capacitors, andinductors) formed on a PCB panel or on any panel or other type ofsubstrate. Note that the system 110 can be employed for otherapplications (e.g., drilling, marking, micro-perforating), and mayinclude various other elements and supporting functionality not shown inFIG. 2, as will be apparent in light of this disclosure.

For trimming operations, the substrate will typically include one ormore untrimmed circuit elements, such as resistors, capacitors, and/orinductors formed contiguous with at least one of dielectric orconductive layers that make up the substrate. Note that an untrimmedelement may also include a portion of the dielectric layer or a portionof the conductive layer, as is the case for an untrimmed embeddedcapacitor. The substrate may include other circuitry andinterconnections (both printed and placed) as well.

For other operations, such as marking, drilling, and perforating, thesubstrate may include any componentry or features that relate to thatparticular substrate′s function, whether it be electrical, mechanical,chemical, textural, or visual in nature. Regardless of the substratestopology and intended function, the principles of the present inventionmay be employed to selectively and accurately direct an energy beam tothe substrate for whatever purpose.

The substrate may be used to form a plurality of substantially identicalcircuits, formed in a repeated pattern, or to form a single circuit(e.g., a computer mother board). On the other hand, the substrate may beused to form a plurality of different circuits formed in a pattern. Thesubstrate may be the same size as the finished circuit board fabricatedtherefrom, or may be subsequently diced up to form a plurality ofsmaller sized finished circuit boards.

System Architecture

As shown in FIG. 2, the system 110 includes laser beam emitter 115operating under the control of the system controller 155. Systemcontroller 155 may include one or more controllers (e.g., programmablemicrocontrollers configured with one or more processors, I/O capabilitysuch as a controller interface having a keyboard and display, memory,and a number of coded processes to carry out desired functionality) forcontrolling the position, velocity and power output of the focused laserbeam and movement of the substrate during machining, as well as duringperiods when the system is not performing machining operations. The beamemitter 115 may include, for example, a laser beam generator such as asolid state or gas laser, but could alternatively be a simple emittingdevice, such as an optic fiber that emits a laser beam generated outsidethe system.

Although the laser beam emitter 115 may be of any type, the laser beamemitter 115 will emit an energy beam at a wavelength that is compatiblewith the type of machining being performed. For example, if a dielectricmaterial is primarily being processed, a CO₂ laser emitting at awavelength of approximately 10 um may be used. If a conductive layer isbeing trimmed, then a solid state laser (e.g., laser diode) emitting ata wavelength of approximately 1.06 um may be used. If the trimming is aphotochemical process, the laser wavelength may be visible orultraviolet light, such a light of approximately 533 nm and shorter.

The emitted laser beam 120 passes through an adjustable beam expander125 (e.g., zoom telescope) to the scan subsystem 130. Adjustment of thebeam expander 125 can be controlled either manually or by the systemcontroller 155 as shown in FIG. 2, as will be discussed herein. The scansubsystem 130 also operates under the control of the system controller155.

The scan subsystem 130 includes beam directing optics 135 and focus lens140. The beam directing optics 135 is provided between the beam expander125 and the focus lens 140, and is capable of directing the laser beamover a selected region of the substrate 150 (or other work piece). Thisselected region is also referred to the selected scan field herein. Thefocus lens 140 is for focusing the directed laser beam to a desired sizeand energy density at the focal point 122. and

The beam directing optics 135 may be implemented with conventionaltechnology, and is capable of scanning a laser beam in one or moredirections. In the FIG. 2 embodiment, a pair of orthogonally mountedgalvanometer mirror scanners (only one shown) serve as the beamdirecting optics 135. Each galvanometer mirror scanner (sometimesreferred to herein as a galvo driven mirror or galvo mirror) includes anangular position transducer for tracking the angular position of themirrors, and a servo driver for controlling the angular rotation of eachdeflecting mirror to direct the laser beam along a path to a desiredposition.

In the FIG. 2 embodiment, the system controller 155 includes all drivingcontrols for the laser beam emitter 115 and the beam directing optics135. However, these controls could be incorporated into one or moresubsystem controllers, separate from the system controller 155, if sodesired.

For resistor trimming operations, the lens 140 may, for example, rangefrom about 1.0 inch in diameter up to about 8 inches in diameter, andhave a field of view that allows the laser beam to be directed overabout a 2 to 4 inch square region or scan field. In one particularembodiment, the focus lens 140 facilitates up to a 3.5 inch square scanfield on the work piece 150. Note, however, that the lens diameter andfield of view can vary from one embodiment to the next, and the presentinvention is not intended to be limited to any one such embodiment.

In any case, the maximum scan field of the scan subsystem 130 is limitedby the field of view of the focus lens 140, and allows a focused beam toaddress selected positions within the field of view. When the scansubsystem 130 is a galvo-based scan subsystem with two mirrors, over anintermediate scan field, the effective pupil of the mirrors may beincreased without increasing the mirror size as would be required formaintaining a large pupil over the largest scan field.

In general, the field of view of lens 140 is usually smaller than thesize of the work piece 150. Typically, all of the machining within ascan field encompassed in the lens 140 field of view is performedwithout moving the work piece 150. The work piece 150 is then moved toposition the next target portion of the work piece 150 in the field ofview of lens 140 for processing. The X-Y stage 152 is adapted to move orstep the work piece 150 so as to position the next target portion of thework piece 150 into the field of view of lens 140.

The X-Y stage 152 can operate, for example, under the control of thesystem controller 155. Alternatively, the X-Y stage 152 operates undermanual control (e.g., hand operated X-Y micrometers), or the under thecontrol of a dedicated controller module that is distinct from thesystem controller 155. In one embodiment, the lens 140 is a telecentriclens and the beam directing optics 135 are positioned substantially at afocal surface of the lens 140 so that the laser beam impingessubstantially normal or perpendicular to the target surface.

The scan subsystem 130 emits a beam that is focused substantially on afeature 145 of the work piece 150, such as a resistor or simply thesurface work piece 150 itself, and has sufficient power to preciselyremove or otherwise machine or process the feature or work piecematerial in a controlled manner. The position of the laser beam 120emitted by the laser beam emitter 115 can be directed by the beamdirecting optics 135 of the scan subsystem 130 to impinge on the focalsurface within the field of view of the lens 140.

The power and modulation of the laser beam can be controlled, forexample, by laser control signals issued by the controller 155 to theemitter 115. Likewise, the desired positioning and motioncharacteristics of the laser beam 120 can be controlled by scan controlsignals issue by the system controller 155 to the scan subsystem 130.The system controller 155 of the embodiment shown in FIG. 2 is generallyprogrammed or otherwise configured to control the operation of theentire machining system. However, numerous control schemes will beapparent in light of this disclosure.

The focus lens 140 focuses the beam so that the beam impinges focalpoint 122 on the feature 145 of work piece 150 (or on the work pieceitself) to perform the desired machining. In one particularimplementation, the feature 145 is a film resistor and work piece 150 isa substrate on which the film resistor is formed. The directed beamimpinges on a resistor to perform a laser trimming operation, whichgenerally increases the resistance of the resistor to some target value.However if, for example, the applicable operation required drilling anaperture or perforation in the work piece 150, then the feature 145could be a target spot on the surface of the work piece 150, where thelaser beam would be focused to impinge on that target spot.

As previously stated, the adjustable beam expander 125 can be a zoomtelescope. In such an embodiment, the zoom telescope varies the pupilsize of the beam entering the scan subsystem 130. Thus, by controllingoperation of the zoom telescope, the effective entrance pupil of thebeam entering the scan subsystem 130 can be adjusted as desired. Forexample, using the zoom telescope as depicted in FIG. 2, the beamentering the scan subsystem 130 may have a pupil size which ranges fromsize A to size C, and the focused beam may have corresponding spot sizesranging from A′ to C′ at the point 122, as shown in FIG. 3A. Hence, bycontrolling the operation of the zoom telescope, the spot size can bemodified to better correspond to the desired processing.

The beam expander 125 can be controlled either manually by an operatoror automatically by the system controller 155 (or other such controllingenvironment) to adjust the pupil size of the beam entering the scansubsystem 130, based on the desired spot size. A combination manual andautomatic mode (i.e., semi-automatic) can also be configured, where alower degree of operator involvement is required. Note that the systemcan be configured so that the operator can be relatively non-skilled, inthat express instructions can be presented to the operator (e.g., via amonitor or pre-programmed audio instructions) indicating how to adjust,control, or otherwise manipulate the beam expander 125 to provide adesired pupil size.

Adjustable Pupil Size

Thus, the beam expander 125 can be operated to vary the pupil size ofthe beam entering the scan subassembly 130 from pupil size A, to pupilsize B, to pupil size C, which in turn results in the spot size at thepoint 122 varying from spot size A′, to spot size B′, to spot size C′,respectively. As shown in FIG. 3B, pupil size A, which is the smallest,results in focus spot size A′, which is optimized to be the largestwithout substantial degradation over the largest scan field 310 of thefocus lens 140. Pupil size B results in an optimized intermediate spotsize B′ without substantial degradation over an intermediate scan field320. Pupil size C, is the largest pupil size, and results in thesmallest spot size C′ without substantial degradation over the smallestoptimized scan field 330. Within any scan field, the spot size may beincreased by decreasing the beam expansion ratio of the laser beam. Notethat when the scan field is limited by degradation, the beam cannot beexpanded unless the scan field is reduced.

Adjustable Scan Field

FIG. 4 depicts various shaped scan fields 410, 420, 430 and 440 withinthe lens field of view 450, which are achieved by controlling the beamdirecting optics 135 to correspond to the optimized scan field (e.g.,via signals from the system controller 155). By controlling theadjustable beam expander 125 or otherwise modifying the beam pupil, theoptimized combinations of spot sizes A′, B′ and C′ and scan field sizes410, 420, 430 and 440 can be accommodated as shown in FIG. 4.

The optimized spot sizes and scan field sizes are achieved bycontrolling the entrance pupil to change the spot size, and bycontrolling the scan subsystem 130, and more particularly the beamdirecting optics 135, to change the scan field size. The control can beautomatic (e.g., carried out by controller 155) or semi-automatic (e.g.,carried out by controller 155 in part and by an operator in part) ormanually (e.g., carried out by an operator).

An optimized scan field may be determined within a field of view inconjunction with motion of the X-Y stage 152. A different area of thework piece 150 can be stepped to using the stage 152, to process furtherelements within the scan field. If the work piece 150 has a tiledprocessing surface with contiguous segments, the motion of the X-Y stage152 may be determined based on the properties of the scan field shape.For example, controller 155 may control stage 152 in incrementsproportional to the X-Y dimensions of scan field 430. The scan fieldmay, in turn, have proportions determined to optimize the scanning speedof the X-Y stage 152.

Referring to FIG. 3B, scan field 310 may contain an accuracyrequirement. Scan field 320, which is smaller than 310, may have anincreased accuracy due to the decreased scan field size. Scan field 330,which is the smallest scan field, may have the highest level of accuracydue to the smallest field size. As the scan fields are reduced from 310to 320 to 330, the non-telecentric error of a non-telecentric imagingsystem will be reduced in sequence from the largest scan field 310through 320 to the smallest scan field 330.

System Control

FIG. 5 illustrates a block diagram of the controller 155 configured inaccordance with an embodiment of the present invention. As shown, thecontroller 155 includes a control processor 510 having an interconnectedprocessor 512 and memory 514. Note that memory 514 could be multiplememory devices including, for example, random access memory, read onlymemory, floppy disk memory, hard disk memory, and/or other types ofmemory. The processor 512 interacts with the memory 514 to function inaccordance with programmed instructions stored on the memory 514 and tostore or access data in the memory 514.

The control processor 510 is interconnected to a display monitor 520 andcontrols the display of relevant information to the system operator.Input devices including a keyboard 530 and mouse 540 are also provided.These devices can be utilized by the operator to input data to thecontrol processor 510. A connection to a communications network is alsoprovided to allow inputs and system programming from a remote location.The control processor 510 is also interconnected to the laser beamemitter 115 and scan subsystem 130. The control processor 510 may beoptionally connected to the adjustable beam expander 125.

In operation, the control processor unit 510 receives operator inputsvia the keyboard 530, mouse 540, data ports (e.g., X-Y stage data portsand RS232 data port), or communications network. The control processor510 processes these inputs in the processor 512, in accordance with theprogrammed instruction stored in the memory 514, to generate controlsignals to the laser emitter 115, to the scan subsystem 130, andoptionally to the beam expander 125.

FIG. 6 depicts a lookup table that can be stored in the memory 514 ofthe control processor 510 and used by the processor 512 to generatecontrol signals to the laser emitter 115, the scan subsystem 130, thebeam expander 125 and/or the display monitor 520.

As shown in FIG. 6, a portion of the lookup table includes a columnhaving each of various scan field sizes. A row associated with each ofthe scan field sizes has a set of parameters for scanning the galvomirror(s) over the selected field size/shape. Accordingly, an operatorcan input a scan field size, such as scan field size 610 correspondingto the typical square scan field 410 shown in FIG. 4, and the processor512 will process the input scan field size 610 by accessing the lookuptable of FIG. 6 in the memory 514 to determine that the galvo mirrormust be rotated to correspond to 610′. The processor 512 then generatesa scan control signal that is transmitted to the scan subsystem 130. Inaccordance with the received scan control signal, the galvo drivenmirror (beam directing optics 135) is operated to correspond to 610′thereby establishing the desired scan field.

The operator may also input a feature size, a feature density, oralternatively a spot size, which can be processed by the processor 512by accessing the lookup table shown in FIG. 6 in the memory 514 todetermine the appropriate zoom telescope (beam expander 125) operationfor the applicable field size. For example, if the desired spot size isa medium spot size (e.g., 35 microns), the processor 512 can determinethat the zoom telescope must be operated to correspond to b′ asindicated in the fourth column of the lookup table shown in FIG. 6.

Accordingly, the processor 512 will generate control signalscorresponding to the determined zoom telescope adjustment and eithertransmit the control signals to the zoom telescope so that theadjustment is made automatically or to the display monitor 520. If thecontrol signal is transmitted to the display monitor 520, the displaymonitor will present to the system operator with appropriateinstructions for manually adjusting the zoom telescope to correspondwith b′. The adjustment of the zoom telescope will result in a pupilsize B of the beam entering the scan system 130 and a corresponding spotsize B′ of the beam at the focal point 122.

Although only a single listing of each of the scan field sizes for thescan fields depicted in FIG. 4 are shown in FIG. 6, it will berecognized in light of this disclosure that the scan field size columnmay include multiple entries for the same size and shape scan field sothat other possible combinations of scan field size and shape and spotsize are included within the lookup table. It will further be recognizedthat in lieu of a lookup table, the programmed instructions stored atthe memory 514 could include corresponding algorithms that would beexecuted by the processor 512 to generate the desired control signals.Also, memory structures other than lookup tables, such as linked listsand simple indexed data files, can be used to store pertinent controlinformation.

FIG. 6 shows in the column labeled X-Y step size that for differentfield size and shape, the X-Y step parameters (e.g., step time, stepsize, number of steps) can change, for instance, from b″ to a″. Notethat step size can be adjusted for either the X or Y direction, or both.Also, the column labeled calibration shows that the field calibrationmay change with field size and shape, for instance, b″′ and a″′.

The foregoing description of the embodiments of the invention has beenpresented for the purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed. Many modifications and variations are possible in light ofthis disclosure. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto.

1. A flexibly optimized material processing system comprising: a laseremitter configured to emit a laser beam; beam adjusting optics having anadjustable beam expansion ratio, and configured to adjust the emittedlaser beam by adjusting the beam expansion ratio; beam directing opticsconfigured to provide a variable effective pupil corresponding to theadjusted laser beam, the beam directing optics further configured todirect the adjusted beam to one or more targets within a scan fieldcorresponding to at least one selected area of a substrate; a lens,having a field of view encompassing at least the scan field, configuredto focus the directed laser beam onto the one or more targets within thescan field; and a control processor configured to receive inputcorresponding to a material processing parameter and to issue at leastone optimized control signal corresponding to the input to reducedegradation over the field of view based on the at least one materialprocessing parameter wherein one said optimized control signal is anoptimum scan field value corresponding to one of the group of valuesconsisting of the effective pupil size of the beam directing optics, afocused laser beam spot size, a positional accuracy, a scanning speed, amaterial handling step size of a motion system, and a telecentricityvalue.
 2. The system of claim 1 wherein the at least one optimizedcontrol signal is an optimum material handling step size correspondingto one of the group of values consisting of a scan field dimension, astep period of a motion system, a substrate dimension, and a dimensionof a selected area of a substrate.
 3. The system of claim 1 wherein thematerial processing parameter is one of the group of parametersconsisting of a spot size, a substrate dimension, a dimension of aselected area of a substrate, an orientation of a selected area of asubstrate, a packing density, a step time of a motion system, a stepsize of a motion system, a number of steps of a motion system, a scanspeed, a positional accuracy, a telecentricity value, and a desired spotquality.
 4. The system of claim 1 wherein the controller is configuredto determine at least one of the group of values consisting of anoptimized value of the beam expansion ratio, a scan field dimension, anda material handling step size of a motion system based on the materialprocessing parameter.
 5. The system of claim 1 wherein: the beamexpansion ratio is a first value, and the scan field is a first scanfield; the beam adjusting optics are further configured to again adjustthe beam expansion ratio from the first value to a second value; and thebeam directing optics are further configured to direct the againadjusted beam to a target within the second scan field.
 6. The system ofclaim 5 wherein the first scan field has a first size and the secondscan field has a second size.
 7. The system of claim 5 wherein the firstscan field has a first shape and the second scan field has a secondshape.
 8. The system of claim 1 wherein the beam adjusting optics aremanually operated to adjust the beam expansion ratio according to anoptimum beam expansion ratio value determined by the controller.
 9. Thesystem of claim 1 further comprising: a control processor configured toreceive an input identifying the scan field and to issue scan controlsignals based on the received input, wherein the beam directing opticsare further configured to direct the adjusted beam in accordance withthe issued scan control signals.
 10. The system of claim 1 furthercomprising: a control processor configured to receive an inputcorresponding to a focused beam spot size and to issue spot size controlsignals based on the received input, wherein the beam adjusting opticsare further configured to adjust the beam expansion ratio in accordancewith the issued spot size control signals.
 11. The system of claim 1further comprising: a control processor configured to receive an inputcorresponding to a beam spot size and to issue spot size control signalsbased on the received input; and a display monitor configured to displayparameters for manually operating the beam adjusting optics to adjustthe beam expansion ratio in accordance with the issued spot size controlsignals.
 12. The system of claim 1 wherein: the beam adjusting opticscomprise a zoom telescope; and the beam directing optics comprise one ormore galvanometer mirror scanners.
 13. The system of claim 1 furthercomprising: a control processor configured to receive an inputidentifying the scan field and to issue motion control signals based onthe received input; and a motion system configured to move a work piecerelative to the scan field in accordance with the issued motion controlsignals.
 14. The system of claim 1 wherein the field of view of the lensencompasses at least a first scan field and a second scan field, and isfurther configured to focus a first directed laser beam with a firsteffective pupil size onto one or more targets within the first scanfield, and to focus a second directed laser beam with a second effectivepupil size onto one or more targets within the second scan field,wherein at least one scan field size is limited by spot size degradationover the field of view.
 15. The system of claim 1 further comprising: amotion system configured to move a work piece containing at least onetarget relative to the scan field, and to position the at least onetarget within the scan field for processing.
 16. The flexibly optimizedmaterial processing system of claim 1 further comprising a controllerinterface.
 17. A material processing system comprising: an emitterconfigured to emit a laser beam; a control processor configured toreceive input and issue optimized control signals corresponding to theinput; beam expansion ratio adjusting optics configured to adjust theemitted laser beam in accordance with at least one of the optimizedcontrol signals; a lens, having a field of view, configured to focus theadjusted beam onto one or more targets within a scan field that is aselected area of a substrate and is encompassed by the field of view;and beam directing optics configured to direct the adjusted beam to atleast one of the one or more targets within the scan field wherein atleast one optimized control signal is optimized to reduce degradationover the field of view and wherein one said optimized control signal isan optimum scan field value corresponding to one of the group of valuesconsisting of the effective pupil of the beam directing optics, afocused laser beam spot size, a positional accuracy, a scanning speed, amaterial handling step size of a motion system, and a telecentricityvalue.
 18. The system of claim 17 wherein: the scan field is a firstscan field; the beam expansion ratio adjusting optics are furtherconfigured to again adjust the emitted laser beam; the lens is furtherconfigured to focus the again adjusted beam onto one or more targetswithin a second scan field encompassed by the field of view; and thebeam directing optics are further configured to direct the againadjusted beam within the second scan field.
 19. The system of claim 17wherein the beam directing optics are further configured to direct theadjusted beam in accordance with at least one of the optimized controlsignals.
 20. The system of claim 17 further comprising: a motion systemconfigured to move a work piece relative to the scan field in accordancewith at least one of the control signals.
 21. The material processingsystem of claim 17 wherein the control processor comprises a controllerinterface.
 22. The material processing system of claim 17, said controlprocessor comprising a connection to a communications network forallowing inputs from a remote location.
 23. A flexibly optimizedmaterial processing system comprising: a laser emitter configured toemit a laser beam; beam adjusting optics having an adjustable beamexpansion ratio, and configured to adjust the emitted laser beam byadjusting the beam expansion ratio; beam directing optics configured toprovide a variable effective pupil corresponding to the adjusted laserbeam, the beam directing optics further configured to direct theadjusted beam to one or more targets within a scan field correspondingto at least one selected area of a substrate; a lens, having a field ofview encompassing at least the scan field, configured to focus thedirected laser beam onto the one or more targets within the scan field;and a control processor configured to receive input corresponding to amaterial processing parameter and to issue at least one optimizedcontrol signal corresponding to the input to reduce degradation over thefield of view based on the at least one material processing parameterwherein one said optimized control signal is an optimum effective pupilsize of the beam directing optics corresponding to a scan fielddimension.
 24. The system of claim 23 wherein the beam adjusting opticsare manually operated to adjust the beam expansion ratio according to anoptimum beam expansion ratio value determined by the controller.
 25. Thesystem of claim 23 further comprising: a control processor configured toreceive an input identifying the scan field and to issue scan controlsignals based on the received input, wherein the beam directing opticsare further configured to direct the adjusted beam in accordance withthe issued scan control signals.
 26. The system of claim 23 wherein: thebeam adjusting optics comprise a zoom telescope; and the beam directingoptics comprise one or more galvanometer mirror scanners.
 27. The systemof claim 23 further comprising: a control processor configured toreceive an input identifying the scan field and to issue motion controlsignals based on the received input; and a motion system configured tomove a work piece relative to the scan field in accordance with theissued motion control signals.
 28. The system of claim 23 wherein thefield of view of the lens encompasses at least a first scan field and asecond scan field, and is further configured to focus a first directedlaser beam with a first effective pupil size onto one or more targetswithin the first scan field, and to focus a second directed laser beamwith a second effective pupil size onto one or more targets within thesecond scan field, wherein at least one scan field size is limited byspot size degradation over the field of view.
 29. The system of claim 23further comprising: a motion system configured to move a work piececontaining at least one target relative to the scan field, and toposition the at least one target within the scan field for processing.